Citral dimethyl acetal (CAS 7549-37-3) — Citrus Top to middle Note Fragrance Ingredient
Citral dimethyl acetal
CAS 7549-37-3
What Is Citral dimethyl acetal?
Citral dimethyl acetal is a synthetic fragrance ingredient used to create fresh, citrusy notes in perfumes and household products. It’s commonly found in air fresheners, cleaning supplies, and citrus-themed fragrances. This ingredient matters because it provides a stable, long-lasting citrus character that doesn’t degrade quickly like natural citrus oils, making products smell fresher for longer periods.
Safety Profile
USE WITH AWARENESSWhat Does Citral dimethyl acetal Smell Like?
Citral dimethyl acetal opens with a bright, lemony burst reminiscent of freshly zested citrus peel, though slightly sweeter and more candied than natural citral. As it evolves, the sharpness mellows into a smooth, herbal-green character with whispers of verbena and lemongrass. The dry-down reveals a subtle woody undertone that adds depth and longevity, creating a sophisticated citrus accord that lingers far longer than natural citrus oils. Unlike fleeting citrus top notes, this acetal maintains its character for hours, making it invaluable for citrus-themed fragrances that need staying power.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used to enhance the citrus freshness while providing stability to the top notes, complementing the bergamot and rosemary for a timeless masculine cologne.
Adds a crisp, long-lasting lemon accent to the Sicilian citrus opening, helping maintain brightness throughout the fragrance’s development.
Provides a stable citrus foundation in this unisex classic, blending with green tea and jasmine for a clean, refreshing effect.
Used to create the illusion of freshly squeezed citrus in this soapy-clean fragrance, where its stability prevents top note degradation.
Enhances the classic citrus bouquet with a modern twist, adding depth and longevity to the traditional cologne structure.
2D Molecular Structure
SMILES: COC(OC)C=C(C)CCC=C(C)C
Chemistry, Properties & Perfumer Guide
The Chemistry
Citral dimethyl acetal is an acetal derivative of citral (a mixture of geranial and neral), formed through acid-catalyzed reaction with methanol. This chemical modification protects the reactive aldehyde groups of citral, dramatically improving its stability against oxidation while maintaining the desirable citrus character. The acetal formation creates a chiral center, though the commercial material is typically used as a racemic mixture. Industrial synthesis involves direct acetalization of citral with methanol in the presence of an acid catalyst like p-toluenesulfonic acid, followed by neutralization and purification.
Physical & Chemical Properties
| Appearance | Colorless to pale yellow liquid |
|---|---|
| Boiling Point | Approx. 230 °C |
| Density | ~0.89 g/cm³ |
| Refractive Index | ~1.46 |
| Solubility | Insoluble in water, soluble in alcohol and oils |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 1-3% | Up to 5% | For stable citrus top notes |
| Functional Products | 0.1-0.5% | Up to 1% | In detergents and cleaners |
| Soaps | 0.2-0.8% | Up to 1.5% | Resistant to alkaline hydrolysis |
| Candles | 0.5-2% | Up to 3% | Heat-stable citrus note |
Classic Accords
Tip: Use to extend citrus top notes in fragrances where oxidation stability is crucial, particularly in products exposed to air or light.
Alternatives & Comparisons
The natural precursor, more authentic but less stable, suitable for natural formulations where oxidation can be controlled.
For a more intense, candied lemon character when higher impact is desired, though less green in character.
When a more diffusive, nitrile-type citrus is needed, though with different odor characteristics.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No IFRA restrictions currently apply to citral dimethyl acetal (2023). The compound is not classified as an allergen under IFRA standards.
EU Allergen Declaration
Not listed in EU Annex III of Regulation (EC) No 1223/2009 as a cosmetic allergen.
GHS Classification
RIFM Assessment
RIFM has evaluated citral dimethyl acetal and found it safe for current fragrance use levels based on available data.
Sustainability
As a synthetic material, citral dimethyl acetal avoids the agricultural impacts of natural citrus oil production. Its stability reduces waste from product degradation. The synthesis typically starts from petrochemical feedstocks, though bio-based routes from pinene are being developed. Its efficiency (less material needed compared to natural citral) and longevity contribute to reduced environmental impact over the product lifecycle.
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References
- Bauer, K. et al. (2001). Common Fragrance and Flavor Materials. Wiley-VCH. ISBN 978-3-527-30364-6
- Sell, C. (2006). The Chemistry of Fragrances. RSC Publishing. ISBN 978-0-85404-824-3
- IFRA Standards Library IFRA 2023
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorPhysicochemical Properties
DTXSID: DTXSID8044832
Physical Properties
| Molecular Weight | 198.306 g/mol🔬 EPA CompTox |
| Density | 0.887 g/cm^3🔬 EPA CTX |
| Boiling Point | 233.147 °C📊 OPERA |
| Melting Point | -48.354 °C📊 OPERA |
| Flash Point | 81.075 °C📊 OPERA |
| Refractive Index | 1.45 Dimensionless📊 OPERA |
| Molar Volume | 226.55 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 3.28 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 3.28 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 3.28 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 5.73 Log10 unitless📊 OPERA |
| Water Solubility | 0.006 mol/L📊 OPERA |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.056 mmHg📊 OPERA |
| Viscosity | 1.646 cP📊 OPERA |
| Surface Tension | 25.525 dyn/cm📊 OPERA |
| Thermal Conductivity | 132.866 mW/(m*K)📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 18.46 Ų💻 Computed |
| H-Bond Donors | 0 count💻 Computed |
| H-Bond Acceptors | 2 count💻 Computed |
| Rotatable Bonds | 6 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 60.893 cm^3/mol📊 OPERA |
| Polarizability | 24.14 Å^3📊 OPERA |
Data Sources:
🔬 EPA Experimental data from U.S. EPA CompTox Chemicals Dashboard & CTX APIs. 📊 OPERA Predicted using EPA's OPERA QSAR models. 💻 Computed Calculated from SMILES using RDKit.
